TWI445580B - Method and apparatus for applying a topcoat to a golf ball surface - Google Patents

Description

Method and apparatus for applying a topcoat to a golf ball surface

The present invention is directed to methods and apparatus for applying a topcoat to a golf ball surface.

Background of the invention

The golf ball summary comprises a one-piece construction or a number of layers comprising an outer cover surrounding a core. Generally, one or more layers of paint and/or colorless coating are applied to the outer surface of the golf ball. For example, in a typical design, the outer surface of the golf ball is first coated with at least one colorless or pigmentary basecoat primer, followed by at least one application of a clearcoat. The colorless topcoat can serve a variety of different functions, such as protecting the covering material, improving the aerodynamics of the ball flight, preventing yellowing, and/or improving the aesthetics of the ball.

One common topcoat utilizes a solvent-borne two-component polyurethane that is applied to the exterior of a golf ball. This topcoat formulation generally requires the use of a solvent that is a significant source of volatile organic compounds (VOCs) and constitutes an environmental and health concern. Another type of coating-ultraviolet curable coating generally does not require a solvent.

Compressed air is typically used to deliver and spray the coating material. These techniques are prone to uneven and/or improper thick coatings and are also filled in the pockets which may negatively compromise the aerodynamic (flying) characteristics of the golf ball. In the case of UV coatings, oxygen present in the air may interfere with the action of UV energy transport to the reactants and also readily react with reactants, particularly photoinitiators, so excess reactants are required. .

Summary of invention

A summary of the aspects of the invention is set forth below in order to provide a basic understanding of the invention and its various features. This Summary is not intended to limit the scope of the invention in any way, but merely provides a general summary and context of the more detailed description below.

Aspects of the invention relate to a method for applying a coating or other coating to a surface of a golf ball. One aspect relates to a method for applying a coating to an outer surface of a golf ball. A carrier stream system comprising nitrogen or nitrogen-enriched air is combined in a coating material to form a mixture. The mixture is then sprayed onto the outside of the golf ball.

A carrier stream system that typically contains nitrogen or is enriched to air having from about 90 to 99.5% nitrogen provides a reduced application time and increased transfer efficiency relative to a compressed air delivery system. The process also does not require long drying times for water-borne materials. The process further provides the following effects: reduced material usage, extended flash time, static removal, polarity change to attract paint on the ball surface, reduced overspray, reduced filter usage, surface moisture, and removal of solid impurities Eliminate density variability in the air, eliminate solvent cracking (for example, micropores formed by trapping the solvent under the coating), and reduce VOC emissions. Other advantages over systems and methods based on compressed air delivery include reduced coating thickness, reduced variation in coating thickness and average thickness, reduced mooring at the center of the pit, and an ideal edge value closer to 1.0. Faster curing time, lower viscosity, less material usage, lower material flow rate, reduced atomizing air pressure, and shorter drying time.

Simple illustration

The invention and its particular advantages can be more completely understood by reference to the following detailed description of the accompanying drawings in which: FIGS. 1 and 1A are schematic cross-sectional views showing a golf ball having a coating thereon; Figure 2A shows a coating device that can apply a coating to a golf ball using a nitriding-enriched air delivery; Figures 3 and 3A show the thickness distribution of the topcoat across a pit pattern in microscopic scale; Figure 3 shows a uniform thickness, while Figure 3A shows the poking in the bottom of the pit that may occur when using the conventional coating method; Figure 4 shows the golf for the coating applied by the nitriding and air-compressed air delivery Average coating thickness of the ball surface (bottom, middle and top); Figure 5 shows the overall golf ball coating thickness compared to compressed air delivery and nitrogen-enriched air delivery; Figure 6 shows the applied coating for compressed air delivery The variability measured in the pit location (refraction, edge, slope, center, slope, edge and crease) of the covering; Figure 7 shows the concave of the coating applied by the nitriding-enriched air transport The variability measured in the location (refraction, edge, slope, center, slope, edge and crease); Figure 8 compares the average thickness of the measurements shown in Figures 6 and 7; Figure 9 shows the The edge ratio (bottom, middle, top) of the coating applied by compressed air delivery and nitrogen-enriched air transport; Figure 10 shows the average edge ratio of the coatings recorded in Figure 9.

Detailed description of the preferred embodiment

In the following description of various example structures, reference is made to the drawings, which are incorporated herein by reference in the drawings in the drawings in the FIGS In addition, other specific configurations of the components and structures may be utilized, and structural and functional modifications may be made without departing from the scope of the invention. Also, although the terms "top", "bottom", "front", "back", "back", "side", "bottom side", "top", and the like may be used in this specification to describe the present invention. The various example feature configurations and elements are used herein for convenience, such as in the exemplary orientation shown in the figures and/or orientation in typical applications. Nothing in this specification should be considered to require a specific three-dimensional or spatial orientation of the structure.

A. General description of golf and manufacturing systems and methods

The golf ball can have varying configurations, such as a one-piece ball, a two-piece ball, a three-piece ball (including a winding ball), a four-piece ball, and the like. The differences in performance characteristics caused by these different types of structures can be quite significant. In general, golf balls can be classified as solid or wound balls. Having a crosslinked rubber core (such as polybutadiene crosslinked by zinc diacrylate and/or a similar crosslinking agent) typically encapsulated by a hybrid coating such as an ionic polymeric resin The two-piece solid ball system is popular with many casual golfers. The combination of core and cover material provides a relatively "hard" ball that is hardly destroyed by the golfer and imparts a high initial velocity to the ball resulting in an improved distance. Because the ball forming material is very rigid, the two-piece ball tends to have a hard "feel" when struck with a bat. By the same token, these balls have a relatively low spin rate due to hardness, which also helps provide a larger distance.

The winding ball is generally composed of a liquid or solid center surrounded by a stretched elastomer material and covered with a durable covering material such as an ionic polymer resin, or a rubber or polyamine base. A soft covering material such as an acid ester. The winding ball is generally considered to be a performance golf ball and has good toughness, ideal swirling characteristics, and tactile sensation when struck by a golf club. However, winding balls are generally difficult to manufacture compared to solid golf balls.

Recently, three- and four-piece balls have been commonly used as ball for ordinary casual golfers and as a performance ball for professional and other elite players.

A variety of different golf balls have been designed to provide specific performance characteristics. These feature summaries include the initial speed and spin of the golf ball, which can be customized for a variety of different types of players. For example, a particular player prefers a ball with a high spin rate to control and stop the golf ball near the green. Other players prefer balls with low spin rate and high toughness to reach maximum distance. In general, a golf ball containing a hard core and a soft cover will have a high spin rate. Conversely, a golf ball containing a hard cover and a soft core will have a low spin rate. Golf balls with a hard core and a hard cover are generally highly tough for distance, but are hard to touch and difficult to control near the green.

A modified multi-layer core, such as a double overlay, a dual core layer, and/or a ball having an intermediate layer between the cover and the core, has been modified by modifying a typical single-layer core and single cover layer configuration. The carrying distance of the two-piece ball that I saw. Three and four-piece balls are common and available today. Aspects of the invention can be applied to all types of configurations, including the various coiled, solid, and/or multilayer ball configurations described above.

1 and 1A show an example of a golf ball 10 having a core 12, an intermediate layer 14, a cover 16 having a plurality of dimples 18, and a topcoat applied to the outer surface of the golf ball 10. Layer 20. The golf ball 10 may alternatively be one piece such that the core 12 represents the entirety of the golf ball 10 and a plurality of dimples are formed on the core 12. The ball 10 can also have any other configuration, including the various example configurations described herein. The thickness of the topcoat 20 is generally significantly less than that of the cover 16 or boundary layer 14, and may be, for example, between about 5 and about 25 [mu]m. The topcoat 20 should have minimal effect on the depth and volume of the pits 18.

The cover 16 of the golf ball 10 can be made of any number of materials such as ionic polymeric, thermoplastic, elastomeric, urethane, rubber (natural or synthetic), polybutadiene, or combinations thereof. An optional primer or base coat can be applied to the outer surface of the cover 16 of the golf ball 10 prior to application of the coating.

center

A golf ball may, for example, form a center with a low compression, but still exhibit a COR that completes the ball and an initial velocity that is similar to the conventional two-piece distance ball. The center can have, for example, a compression of about 60 or less. The completed ball with these centers measured a COR of about 0.795 to about 0.815 at an in-velocity rate of 125 ft/s. "COR" refers to the recovery factor, which is obtained by dividing the rebound speed of the ball by its initial (ie, incoming) speed. This test is performed by firing a sample out of a vertical gun at a range of test speeds (e.g., from 75 to 150 ft/s). A golf ball with a high COR dissipates a smaller proportion of its total energy when it impacts the plate and bounces off the plate as compared to a ball with a lower COR.

The terms "point" and "compression point" refer to the compression scale or the compression scale based on the ATTI engineering compression tester. This scale, as is well known to those skilled in the art, is used to determine the relative compression of a center or ball.

The center may have, for example, a Shore C hardness of about 65 to 80. The center can have a diameter of from about 1.25 吋 to about 1.5 。. The substrate composition for forming the center may include, for example, polybutadiene and about 20 to 50 parts of a diacrylic acid, a dimethacrylic acid or a metal salt of monomethacrylic acid. If desired, the polybutadiene can also be blended with other elastomers known in the art, such as natural rubber, styrene butadiene, and/or isoprene, to further modify the properties of the center. When a mixture of elastomers is used, the amount of other ingredients in the center composition is typically based on 100 parts by weight of the total elastomer mixture.

The metal salts of diacrylic acid, dimethacrylic acid and monomethacrylic acid include, but are not limited to, those in which the metal is magnesium, calcium, zinc, aluminum, sodium, lithium or nickel. For example, zinc diacrylate provides a high initial speed for golf balls in the US Golf Association (USGA) test.

Free radical initiators are commonly used to promote crosslinking of diacrylic acid, dimethacrylic acid or monomethacrylic acid metal salts and polybutadiene. Suitable free radical initiators include, but are not limited to, peroxide compounds such as dicumyl peroxide; 1,1-bis(tert-butylperoxy) 3,3,5-trimethylcyclohexane; (tert-butylperoxide) diisopropylbenzene; 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane; or di-tert-butyl peroxide; and mixtures thereof. The initiator at 100% activity can be added from an amount between about 0.05 to about 2.5 pph of 100 parts butadiene, or butadiene mixed with one or more other elastomers. The amount of initiator added is often from about 0.15 to about 2 pph, more usually from about 0.25 to about 1.5 pph. The golf center can incorporate 5 to 50 pph of zinc oxide (ZnO) into a zinc diacrylate-peroxide cure system that crosslinks polybutadiene during the core molding process.

The center composition can also include a filler that is added to the elastomeric composition to adjust the density and/or specific gravity of the center. Non-limiting examples of fillers include zinc oxide, barium sulfate, and regrind, such as a core molded matrix that is ground to a recycled particle size of about 30 mesh. The amount and type of filler utilized is controlled by the quantity and weight of the other components in the composition. Please note that USGA has established a maximum golf weight of 1.620 oz. The filler typically has a specific gravity of from about 2.0 to about 5.6. The center may have a lower amount of filler to reduce the specific gravity of the center.

The specific gravity of the center may range, for example, from about 0.9 to about 1.3, depending on factors such as the center, the cover, the size of the intermediate layer and the finished ball, and the specific gravity of the cover and the intermediate layer.

Other components may also be used in amounts sufficient to achieve typical use, such as accelerators such as tetramethyl thiram, processing aids, treatment oils, plasticizers, dyes and pigments, antioxidants, and those skilled in the art. Other additives are well known.

middle layer

The golf ball may also have one or more intermediate layers such as dynamically vulcanized thermoplastic elastomers, functionalized styrene-butadiene elastomers, thermoplastic rubbers, thermoset elastomers, thermoplastic urethanes, metallocenes A polymer, a thermosetting urethane, an ionic polymer resin, or a blend thereof is formed. For example, an intermediate layer can include a thermoplastic or thermosetting polyurethane. Non-limiting commercially available dynamically vulcanized thermoplastic elastomer systems including SANTOPRENE , SARLINK , VYRAM , DYTRON , and VISTAFLEX . SANTOPRENE It is a dynamically vulcanized PP/EPDM. Examples of functionalized styrene-butadiene elastomers - that is, styrene-butadiene elastomers having functional groups such as maleic anhydride or sulfonic acid, include KRATON FG-1901x and FG-1921x, which are derived from Shell Corporation of Houston, Texas.

Examples of suitable thermoplastic polyurethanes include ESTANE 58133, ESTANE 58134 and ESTANE 58144, which is commercially available from BF Goodrich Company of Cleveland, Ohio.

An example of a metallocene polymer - that is, a polymer that forms a metallocene catalyst - includes those commercially available from Sentinel Products of Hannes, MA. Suitable thermoplastic polyesters include polybutylene terephthalate. A polymer comprising at least one member of the group consisting of a monoolefin and a mono- or dicarboxylic acid having an unsaturated mono- or dicarboxylic acid having 3 to 12 carbon atoms and an ester thereof (the polymer contains 1 to 1) 50% by weight of an unsaturated mono- or dicarboxylic acid and/or its ester) to obtain a thermoplastic ionic polymer resin. More particularly, low modulus ionic polymers such as acid-containing ethylene copolymer ionic polymers include E/X/Y copolymers wherein E is ethylene and X is a softening comonomer such as acrylate or methyl. Acrylate. Non-limiting examples of ionic polymer resins include SURLYN And LOTEX They are available from DuPont and Exxon, respectively.

Alternatively, the intermediate layer may be a blend of a first component and a second component, wherein the first component is a dynamically vulcanized thermoplastic elastomer, a monofunctional styrene-butadiene elastomer, a thermoplastic or thermosetting polyurethane or a metallocene polymer, and the second component is a thermoplastic or thermosetting polyurethane, a thermoplastic polyether ester or a polyether decylamine, a thermoplastic ionic A polymer resin, a thermoplastic polyester, another dynamically vulcanized elastomer, another functionalized styrene-butadiene elastomer, another metallocene polymer or a blend thereof. At least one of the first and second components may comprise a thermoplastic or thermosetting polyurethane.

An intermediate layer can also be formed from a blend containing a copolymer of ethylene methacrylic acid/acrylic acid. Non-limiting examples of acid-containing ethylene copolymers include ethylene/acrylic acid; ethylene/methacrylic acid; ethylene/acrylic acid/n- or isobutyl acrylate; ethylene/methacrylic acid/n- or isobutyl acrylate; ethylene/ Acrylic/methacrylic acid ester; ethylene/methacrylic acid/methacrylic acid ester; ethylene/acrylic acid/isobornyl acrylate or methacrylate and ethylene/methacrylic acid/isobornyl acrylate or methacrylic acid ester. Commercially available examples of ethylene methacrylic acid/acrylic acid copolymers include NUCREL Polymer, available from DuPont.

Alternatively, an intermediate layer can be formed from a blend comprising a ethylene methacrylic acid/acrylic acid copolymer and a second component comprising a thermoplastic material. Suitable thermoplastic materials for use in the intermediate blend include, but are not limited to, polyester ester block copolymers, polyether ester block copolymers, polyether guanamine block copolymers, ionic polymer resins, dynamically vulcanized a thermoplastic elastomer; a styrene-butadiene elastomer to which a functional group such as maleic anhydride or sulfonic acid is attached, a thermoplastic polyurethane, a thermoplastic polyester, a metallocene polymer, and/or a mixture thereof Admixture.

The intermediate layer often has a specific gravity of about 0.8 or more. In some examples, the intermediate layer has a specific gravity greater than 1.0, such as from about 1.2 to about 1.3. The specific gravity of the intermediate layer can be adjusted, for example, by adding a filler such as barium sulfate, zinc oxide, titanium dioxide, and combinations thereof.

The interlayer blend may have a flexural modulus of less than about 10,000 psi, often from about 5,000 to about 8,000. The intermediate layer often has a Shore D hardness of about 35 to 50. The intermediate layer and core construction can together have a compression of less than about 65, often from about 50 to about 65. Typically, the intermediate layer has a thickness of from about 0.020 吋 to about 0.125 。.

The golf ball may comprise a single intermediate layer or a plurality of intermediate layers. In the case where a ball comprises a plurality of intermediate layers, a first intermediate layer may, for example, comprise a thermoplastic material having a greater hardness than the core. A second intermediate layer can be disposed around the first intermediate layer and can have a greater hardness than the first intermediate layer. The second intermediate layer may be formed of a material such as a polyether or polyester thermoplastic urethane, a thermosetting urethane, and an ionic polymer such as an acid-containing ethylene copolymer ionic polymer.

In addition, a third intermediate layer may be disposed between the first and second intermediate layers. The third intermediate layer may be formed of a plurality of different materials as described above. For example, the third intermediate layer can have a greater hardness than the first intermediate layer.

Cover layer

A golf ball also typically has a cover layer comprising one or more layers of a thermoplastic or thermoset material. A variety of different materials can be used, such as ionic polymer resins, polyurethanes, rubber bands, and blends thereof.

The cover may be formed from a composition comprising very low modulus ionic polymers (VLMIs). As used herein, "very low modulus ionic polymer" or the abbreviation "VLMIs" is an ionic polymer resin further comprising a softening comonomer X, often a (meth) acrylate ester, at about 10 A weight percentage to about 50 weight percent is present in the polymer. The VLMIs are an α-olefin such as ethylene, a softener such as n-butyl acrylate or isobutyl acrylate, and a copolymer of α, β unsaturated carboxylic acid such as acrylic acid or methacrylic acid, wherein the acid At least a portion of the group is neutralized by a magnesium cation. Other examples of softening comonomers include n-butyl methacrylate, methacrylate, and methyl methacrylate. In general, VLMI has a flexural modulus from about 2,000 to about 10,000. VLMIs are sometimes referred to as "soft" ionic polymers.

Plasma-type polymers such as acid-containing ethylene copolymers include E/X/Y copolymers wherein E is ethylene and X is a softening comonomer such as acrylate or methacrylate, presenting from 0 to 50 weight percent of the polymer And Y is acrylic or methacrylic acid, present in a weight percentage of 5 to 35 (usually 10 to 20) of the polymer, wherein the acid unit is neutralized to 1 to 90 percent (typically at least 40 percent) by such as A cation such as lithium, sodium, potassium, magnesium, calcium, barium, lead, tin, zinc or aluminum or a combination of such cations forms an ionic polymer, preferably lithium, sodium and zinc. Specific acid-containing ethylene copolymers include ethylene/acrylic acid, ethylene/methacrylic acid, ethylene/acrylic acid/n-butyl acrylate, ethylene/methacrylic acid/n-butyl acrylate, ethylene/methacrylic acid/isobutyl butyl Acrylate, ethylene/acrylic acid/isobutyl acrylate, ethylene/methacrylic acid/n-butyl methacrylate, ethylene/acrylic acid/methyl methacrylate, ethylene/acrylic acid/methacrylic acid ester, ethylene/methacrylic acid/ Methacrylate, ethylene/methacrylic acid/methyl methacrylate, and ethylene/acrylic acid/n-butyl methacrylate.

To aid in the processing of the cover stock, the ionic polymer can be blended to obtain a cover having the desired characteristics. For this reason, the cover member may be formed of a blend of two or more ionic polymer resins. The blend may include, for example, a very soft material and a relatively hard material. Ionic polymers having different melt flow indices are often used to obtain the desired characteristics of the cover material. SURLYN 8118, 7930, and 7940 have melt flow indices of about 1.4, 1.8, and 2.6 grams per 10 minutes, respectively. SURLYN 8269 and SURLYN Each of 8265 has a melt flow index of approximately 0.9 g/10 min. A blend of ionic polymer resins can be used to form a cover having a melt flow index of from about 1 to about 3 grams per 10 minutes. The cover layer can have a Shore D hardness of, for example, from about 60 to about 70.

The cover summary includes thermoplastic and/or thermoset materials. For example, the cover member can comprise a thermoplastic material such as a urethane or a polyurethane. The polyurethane is a reaction product between a polyurethane prepolymer and a curing agent. The polyurethane prepolymer is a product formed by the reaction between a polyol and a diisocyanate. A catalyst is often used to promote the reaction between the curing agent and the polyurethane prepolymer. In the case of cast polyurethanes, the curing agent is typically a diamine or ethylene glycol.

In another example, a thermoset cast polyurethane can be used. Thermosetting cast polyurethanes utilize a diisocyanate such as 2,4-diisocyanate toluene (TDI), dicyclohexylmethane diisocyanate (HMDI), or p-phenylene diisocyanate (PPDI), and a polyhydric alcohol cured by a polyamine such as diaminodiphenylmethane (MDA), or a trifunctional ethylene glycol such as trimethylolpropane, or such as N, N, N', N'-tetra (2- Prepared by tetrafunctional ethylene glycol such as hydroxypropyl)ethylenediamine. Other suitable thermoset materials include, but are not limited to, thermoset urethane ionic polymers and thermoset urethane epoxies. Other examples of thermoset materials include polybutadiene, natural rubber, polyisoprene, styrene-butadiene, and styrene-propylene-diene rubber.

When the cover member includes more than one layer, such as an inner cover layer and an outer cover layer, various configurations and materials may be suitable. For example, an inner cover layer may surround the intermediate layer and an outer cover layer may be disposed thereon, or an inner cover layer may surround the plurality of intermediate layers. When an inner and outer cover layer construction is used, the outer cover material can be a thermoset material comprising at least one of a castable reactive liquid material and a reaction product thereof, as described above, and can have from about 30 to about 60 Shore D hardness.

The inner cover layer can be formed from a wide variety of hard (e.g., about 65 Shore D or greater), high flexural modulus tough materials that are compatible with other materials of adjacent layers of the golf ball. The inner cover material can have a flexural modulus of about 65,000 psi or greater. Suitable inner cover materials include hard, high flexural modulus ionic polymer resins and blends thereof, which can be provided by providing a cross metal bond to the monoolefin and from a carbon having from 3 to 12 carbon atoms. It is obtained by saturating a polymer of at least one member of a group consisting of mono or dicarboxylic acids and esters thereof, the polymer having 1 to 50% by weight of an unsaturated mono- or dicarboxylic acid and/or an ester thereof. More particularly, the acid-containing ethylene copolymer ionic polymer component comprises an E/X/Y copolymer wherein E is ethylene and X is a softening comonomer such as acrylate or methacrylate to polymerize 0 to 50 weight percent of the substance appears, and Y is acrylic acid or methacrylic acid, which is present in an amount of 5 to 35 weight percent of the polymer, wherein the acid moiety is such as lithium, sodium, potassium, magnesium, calcium, barium, lead, A cation such as tin, zinc or aluminum or a combination of such cations is neutralized by about 1 to 90 percent to form an ionic polymer. Specific examples of acid-containing ethylene copolymers include ethylene/acrylic acid, ethylene/methacrylic acid, ethylene/acrylic acid/n-butyl acrylate, ethylene/methacrylic acid/n-butyl acrylate, ethylene/methacrylic acid/isobutylene Acrylate, ethylene/acrylic acid/isobutyl acrylate, ethylene/methacrylic acid/n-butyl methacrylate, ethylene/acrylic acid/methyl methacrylate, ethylene/acrylic acid/methacrylic acid ester, ethylene/methacrylic acid /Methyl acrylate, ethylene/methacrylic acid/methyl methacrylate, and ethylene/acrylic acid/n-butyl methacrylate.

Examples of other suitable inner cover materials include thermoplastic or thermoset polyurethanes, polyether esters, polyether polyamides, or polyesters, dynamically vulcanized elastomers, functionalized styrene-butadiene elastomers. , metallocene polymers, polyamines such as nylon, acrylonitrile butadiene-styrene copolymer (ABS), or blends thereof.

Manufacturing process

One common technique for making golf balls is a lamination process. In order to form multiple layers around the center, a laminate is first formed. The laminate comprises at least two layers and sometimes three layers. The laminate can be formed by mixing the uncured core material used for each layer and rolling the material into a sheet. Alternatively, the laminate can be formed by mixing the uncured interlayer material and rolling the material into a sheet. Using a roll mill, the laminate sheets can be stacked together to form a laminate having three layers. Alternatively, the sheet can be formed by extrusion.

A laminate can also be formed using an adhesive between the layers of material. For example, an epoxy resin can be used as an adhesive. The adhesive should have good shear and tensile strength, such as a tensile strength above about 1500 psi. The adhesive typically has a Shore D hardness of less than about 60 when cured. The layer of adhesive applied to the sheet should be very thin, such as less than about 0.004 inch thick.

Preferably, each laminate is formed to a thickness that is slightly greater than the thickness of the finished golf ball layer. These thicknesses can each vary, but all have a thickness of preferably less than about 0.1 angstrom. The sheet should have a very uniform thickness.

The next step in the method is to form multiple layers around the center. This can be achieved by placing the two laminates between a top mold and a bottom mold. The laminate can be formed into a cavity in the mold halves. The laminate can then be cut into a pattern that, when joined, will form a layered layer along the center. For example, the laminate can be cut into a figure-eight or barbell-like pattern, similar to a baseball or tennis cover. Other patterns such as curved triangles, hemispherical cups, ovals, or the like, or other patterns that can be joined together to form a layered layer around the center can be used. The pattern can then be placed between the dies and formed into a cavity in the mold halves. A vacuum source is often used to form the laminate into the mold cavity to maintain uniformity in layer thickness.

After the laminate has been formed into the cavity, the center is then inserted between the laminates. The laminate is then compression molded along the center of the periphery under conditions of temperature and pressure well known in the art. The mold halves typically have ports to allow excess layer material to flow from the laminate during the compression molding process. In an alternative to compression molding, the core and/or intermediate layers can be formed by injection molding or other suitable technique.

The next step involves forming a cover around the core of the golf ball. The core, including the center and intermediate layers, may be supported by a plurality of retractable pins in a pair of cover mold halves. The retractable pin can be actuated by conventional means known to those skilled in the art.

After the mold halves are closed with the pins for supporting the core, the covering material is injected into the mold in a liquid state via a plurality of injection jaws or gates such as edge gates or secondary gates. With the edge gates, the resulting golf balls are all interconnected and can be removed from the mold halves together with a large matrix. The secondary gate automatically separates the mold flow path from the golf ball during the shooting of the golf ball from the mold half.

The retractable pin can be retracted after substantially injecting the core into the mold half for a predetermined amount of cover material. The liquid covering material is allowed to flow and substantially fill the cavity between the core and the mold halves while maintaining concentricity between the core and the mold halves. The cover material is then allowed to solidify around the center, and the golf ball is ejected from the mold halves and subjected to a trimming process, including face coating, lacquering, and/or other trimming processes, including processes in accordance with examples of the present invention, as follows describe in detail.

B. General description of coating materials

A variety of different materials can be used to form the topcoat, non-limiting examples of which include thermoplastics, thermoplastic elastomers such as polyurethanes, polyesters, acrylics, low acid thermoplastic ionic polymers, such as containing up to about 15% acid, and UV curable system. The thickness of the topcoat is typically between about 5 and about 25 [mu]m, and in some instances between about 10 and about 15 [mu]m.

Additional additives may be selectively incorporated into the coating material, such as flow additives, fouling/slip additives, adhesion promoters, thickeners, gloss reducers, softeners, cross-linking additives, isocyanates or for roughening Or other agents that produce scratch resistance, optical brighteners, UV absorbers, and the like. The amount of such additives is typically from 0 to about 5% by weight, often from 0 to about 1.5% by weight.

C. General description of coated parts

The coating material can be delivered by a spray gun (fixed or articulated). Examples of components that can be used include heated spray equipment and electrostatic and high volume-low pressure (HVLP) components. The golf ball is typically placed on a work hold where it rotates and passes through a spray zone for a specified time to achieve complete coverage of its exterior surface.

In some aspects, the coating material is delivered to the exterior surface of the golf ball using a carrier fluid comprising nitrogen or nitrogen-enriched air. Nitrogen is clean and dry (anhydrous) in its elemental gaseous state. Nitrogen can be ionized to eliminate problems associated with moisture and statics.

A suitable apparatus for applying a nitriding air to a coating is described in U.S. Patent No. 6,821,315, the disclosure of which is incorporated herein in its entirety by reference. These parts are available from N2 Spray Solutions (N2 Spray) Solutions). Generally, such components are operated by mixing a carrier fluid with a coating material under pressure. The carrier fluid comprises nitrogen-enriched air, which typically contains from about 90 to 99.5% by volume of nitrogen. Nitrogen-enriched air can be produced, for example, by passing air through a hollow fiber membrane as described in the '315 patent.

The temperature of the carrier fluid can be adjusted to optimize coating properties. In general, heating the carrier fluid will reduce viscosity and reduce the need for solvents. Reducing the viscosity will improve flow, aid in atomization and remove solvent, resulting in finer sprays with higher solids content. The carrier fluid can be heated, for example, to a temperature of from about 100 to about 170 °F (38 to 76.6 °C), often from about 150 to about 170 °F (65.6 to 76.6 °C). Other parameters such as pressure may also be suitably adjusted to achieve improved drying characteristics and/or other efficiencies. For example, an atomizing air pressure of about 40 psi (275.8 kPa) can be employed.

The advantages of reducing the amount of solvent include easier spraying, faster flash and evaporation times, and reduced overspray. This in turn reduces the waste of coating material and provides a cleaner working environment that reduces static electricity, resulting in less airborne contaminants.

Nitrogen-enriched air transport can also reduce application time, increase transfer efficiency, reduce drying time (especially for water-borne materials), reduce material usage (for example, about 20% reduction in coating material usage), increase flash Urgent time, change polarity to promote coating to ball surface attraction, reduce filter usage, remove surface moisture, remove solid impurities, eliminate density variability in air, eliminate solvent cracking, eliminate major uncontrollable variables And reduce VOC emissions. The nitrogen-enriched air delivery system can also advantageously return pure nitrogen to the environment. The carrier fluid can be freed to eliminate problems associated with moisture and statics.

Other advantages with respect to compressed air delivery include reduced coating thickness, less variation in coating thickness and average thickness, less undulation in the pits, edge ratios closer to ideal values of 1.0, faster cure times, and lower Material flow rate, and reduced atomizing air pressure. For example, the material flow rate can be reduced from about 50 to about 40 metric tons per minute (cc/min) (20% reduction). The atomizing air pressure can be reduced from about 50 to about 40 psi (344.8 to 275.8 kPa) (20% reduction). The drying time of the coating can be reduced by about 30%, which can reduce the overall coating drying time from a full working period (such as about 8 to 10 hours) to a significantly smaller, thereby reducing the oven time, heating time, overall Output time, etc., and related expenses. Faster drying times, as described above, can help reduce the pit-bottoming effect of the pits.

Another potential advantage is that the reduction in coating thickness can allow for an increase in weight (and potentially a better weight placement) in other desirable locations of the ball, such as the core, cover, cover, and/or other layers, to Improve performance characteristics or achieve other advantages.

D. Specific examples of invention

Referring to Figures 2 and 2A, a coating apparatus 100 for applying a topcoat 20 is shown. The illustrated component 100 has an upper spray head 125A and a lower spray head 125B. The coating material is supplied to the showerheads 125A and 125B via the inlet line 105. A coating material inlet valve, such as solenoid valve 112, and a valve actuation control circuit 110 control the flow of coating material from the inlet line 105 through the spray nozzles contained in the nozzle tip. The heated nitrogen-enriched air is supplied to the upper 125A and lower spray heads 125B via line 115. As shown in FIG. 2A, the golf ball 10 can be placed on a rotating ball holder 130, which facilitates A flat coating is provided over the entire outer surface of the ball.

Figures 2 and 2A show a configuration utilizing two fixed sprinkler heads 125A and 125B. In some examples, three or more stationary sprinkler heads can be used. Alternatively, one or more sprinkler heads can be mounted on a movable, articulated mount (not shown) that will move as the ball moves past the spray booth. This movement can be programmed to apply a uniform coating more well on the outer ball surface.

example

Twelve golf balls were evaluated in order to compare the application of the applied coating with the compressed air delivery and the application of the application with the nitrogen-enriched air. Golf balls 1 through 6 have a solvent based polyurethane topcoat applied by conventional compressed air delivery. Golf balls 7 through 12 have a solvent based polyurethane topcoat applied using the nitrogen-enriched air delivery described herein.

Three sample areas are taken from each ball for measurement, namely a pit at the top, one in the middle, and one at the bottom. Seven cells were analyzed for each sample region.

Cut three samples of each golf ball and take one from the top, middle and bottom. For each sample, the largest pit was taken to compare it to another pit. Each sample was analyzed on both sides of the pit at the creases, edges, slopes, and center. These sections are shown in Figure 3, for example. The reticle refers to the area between the pits; the edge is the intersection between the ridges and the curved slope of the pits; and the center refers to the bottom of the pits.

Referring to Figures 3 and 3A, it is desirable to have the coating have a constant thickness above the surface. Figure 3 shows a coating having the same thickness as the bottom of the pit at the edge of the pit, resulting in an edge ratio of 1.0 (T _edge / T _bottom = 1.0). An edge ratio close to 1.0 represents a uniform thickness. The edge ratio is calculated by dividing the average coating thickness at the edge of the pit by the average coating thickness in the middle of the bottom of the pit. As shown in Fig. 3A, when a conventional coating method such as compressed air delivery is carried out, the coating tends to flow down the edge of the pit and "pod" in the bottom of the pit. This results in a non-uniform coating such that the edge ratio T _edge /T _bottom may be significantly different than 1, in some cases about 0.5 or even less.

The compressed air delivery system provides a thicker coating of a pocket for the golf ball than the method of nitrogen-enriched air delivery (see Figure 3) (see Figure 3A). The compressed air sample has an average thickness of 14.24 μm and a standard deviation of about 3 μm. The nitrogen-enriched air transport sample has an average thickness of 12.2 μm and a standard deviation of about 3.3 to 2.4 μm.

Figure 4 shows the measured average coating thickness taken at the bottom, middle and top of the golf ball. Figure 5 shows the overall thickness of the coating prepared by compressed air and nitrogen-enriched air transport. Thin vertical bars represent the standard deviation. As shown in Figures 4 and 5, the nitriding-enriched air transport results in a reduced overall coating thickness and a smaller thickness variability between the bottom, middle and top portions than compressed air delivery.

Figure 6 compares the various measured cells (chicks, edges, slopes, centers, slopes, edges and creases) in the pits of the golf ball coated with compressed air. Figure 7 shows the same measurement for a golf ball coated with nitrogen-enriched air. It can be seen that the coating applied by the nitrogen-enriched air transport (Fig. 7) is generally finer in each of the measured cell systems than the coating applied by the compressed air transport (Fig. 6). And in different small The zone has a small thickness variability.

Figure 8 compares the average thickness measurements shown by this data from each of the measured cells (Figures 6 and 7). The highest peak of the compressed air sample is centered and also rises at the crease, while the sample prepared by nitriding air transport presents its highest peak at the crease. This feature was found to advantageously affect the ball trajectory and increase the distance.

Figure 9 shows the edge ratio from the six spheres for the bottom, middle and top of the compressed air sample and the nitrogen-enriched air sample. Figure 10 shows the average of the ratios of the edges for the compressed air and nitrogen-enriched air samples. The compressed air sample has an average edge ratio of about 0.9, while the nitrogen-enriched air sample has an average edge ratio of about 1.0.

Although the present invention has been described in detail with reference to specific examples of the present preferred embodiments of the present invention, those skilled in the art will appreciate that the above described systems and methods have many variations and modifications. Therefore, the spirit and scope of the present invention should be broadly defined as the scope of the patent application.

10‧‧‧ Golf

12‧‧‧ core

14‧‧‧Intermediate

16‧‧‧Cover

18‧‧‧ pit

20‧‧‧Face coating

100‧‧‧ Coating device

105‧‧‧Entry line

110‧‧‧Valve actuation control circuit

112‧‧‧ Solenoid valve

115‧‧‧ lines

125A‧‧‧上上头

125B‧‧‧ under the shower head

130‧‧‧Ball holding parts

1 and 1A are schematic cross-sectional views showing a golf ball having a coating thereon; and 2 and 2A are views showing a coating device capable of applying a coating to a golf ball using a nitrogen-enriched air transport Sections 3 and 3A show the thickness distribution of the topcoat across a pit pattern in microscopic order; Figure 3 shows a uniform thickness, while Figure 3A shows the bottom of the pit that may occur when using the conventional coating method. Mooring; Figure 4 shows the use of nitriding and air-compressed air delivery Average coating thickness (bottom, middle and top) of the golf ball surface of the applied coating; Figure 5 shows the overall golf ball coating thickness compared to compressed air delivery and nitrogen-enriched air delivery; Figure 6 shows The variability measured in the pit location (backlash, edge, slope, center, slope, edge and crease) of the applied coating using compressed air delivery; Figure 7 shows the transport for nitriding-enriched air The variability measured in the pit location (backlash, edge, slope, center, slope, edge and crease) of the applied coating; Figure 8 compares the measured values shown in Figures 6 and 7. Average thickness; Figure 9 shows the edge ratio (bottom, middle, top) of the applied coating for compressed air delivery and nitrogen-enriched air transport; Figure 10 shows the average of the coatings recorded in Figure 9. Edge ratio.

10. . . golf

12. . . core

14. . . middle layer

16. . . Cover

18. . . Pit

20. . . Top coat

Claims (25)

A method for applying a topcoat to a surface of a golf ball, comprising: combining a coating material with a carrier fluid containing nitrogen or nitrogen-enriched air to form a mixture; and applying the mixture To the surface of the golf ball. The method of claim 1, wherein the carrier stream system comprises air enriched to a nitrogen having a volume of from about 90 to 99.5%. The method of claim 1, further comprising the step of heating the mixture to a temperature of from about 100 to about 170 °F (38 to 76.6 °C). The method of claim 3, wherein the temperature is from about 150 to about 170 °F (65.6 to 76.6 °C). The method of claim 1, wherein the coating material is a thermoplastic polymer. The method of claim 5, wherein the coating material is a polyurethane. The method of claim 5, wherein the coating material is a polyester. The method of claim 1, wherein the coating on the outer surface of the golf ball has a thickness of from about 5 to about 25 μm. The method of claim 8, wherein the thickness is from about 10 to about 15 μm. The method of claim 1, wherein the nitrogen-enriched air is produced by passing air through a hollow fiber membrane. The method of claim 1, further comprising ionizing the nitrogen-enriched air. The method of claim 1, wherein the coating material and the carrier flow system are premixed and the mixture is sprayed through one or more spray nozzles. The method of claim 1, wherein the coating material is sprayed through the one or more first nozzles, and the carrier fluid is sprayed through the one or more second nozzles to form the mixture. A golf ball having a coating applied by the method of claim 1 of the patent application. A method for applying a polyurethane topcoat to an exterior surface of a golf ball, comprising: combining a polyurethane coating material with a carrier fluid to form a mixture, the carrier fluid containing Enriching air having a nitrogen content of about 90 to 99.5% by volume; heating the mixture to a temperature of from about 100 to about 170 °F (38 to 76.6 °C); and spraying the mixture onto the outer surface of the golf ball to form A coating having a thickness of from about 5 to about 25 [mu]m. The method of claim 15, wherein the temperature is from about 150 to about 170 °F (65.6 to 76.6 °C). The method of claim 15, wherein the thickness is from about 10 to about 15 μm. For example, the method of claim 15 wherein the nitriding air is borrowed Produced by passing air through a hollow fiber membrane. The method of claim 15, further comprising dissociating the nitrogen-enriched air. A golf ball having a coating applied by the method of claim 15 of the patent application. An apparatus for applying a topcoat to a surface of a golf ball, comprising: a coating material supply; a carrier fluid supply comprising nitrogen or nitrogen-enriched air; at least one spray nozzle for applying the coating Covering material and carrier fluid onto the surface of the golf ball; and a working holder for supporting the golf ball. The apparatus of claim 21, further comprising a heat source for heating the carrier fluid. The device of claim 21, wherein the at least one spray nozzle comprises a plurality of fixed sprinkler heads. A device according to claim 21, wherein one or more sprinkler heads are mounted on a movable, articulated mount. The device of claim 21, wherein the working holding member is adapted to rotatably support a plurality of golf balls.